1. Field of the Invention
This invention relates to a variable displacement engine which is capable of controlling the number of operating cylinders, holding part of its cylinders at rest according to the operation condition.
2. Description of the Prior Art
The conventional variable displacement engines of this sort are usually operated with part of the cylinders at rest, for example, in a low load condition to enhance the combustion efficiency thereby to prevent emissions of toxic exhaust gases or to raise the load factor for improving the fuel cost by reduction of pumping losses.
However, such conventional variable displacement engines have a problem that it takes an unduly long time for warming up if the engine is put in the partial displacement operation when in cold state.